tools/aapt2/cmd/Diff.cpp - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2016 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "android-base/macros.h"

 #include "Flags.h"
 #include "LoadedApk.h"
 #include "ValueVisitor.h"
 #include "process/IResourceTableConsumer.h"
 #include "process/SymbolTable.h"

 using ::android::StringPiece;

 namespace aapt {

 class DiffContext : public IAaptContext {
  public:
   DiffContext() : name_mangler_({}), symbol_table_(&name_mangler_) {
   }

   PackageType GetPackageType() override {
     // Doesn't matter.
     return PackageType::kApp;
   }

   const std::string& GetCompilationPackage() override {
     return empty_;
   }

   uint8_t GetPackageId() override {
     return 0x0;
   }

   IDiagnostics* GetDiagnostics() override {
     return &diagnostics_;
   }

   NameMangler* GetNameMangler() override {
     return &name_mangler_;
   }

   SymbolTable* GetExternalSymbols() override {
     return &symbol_table_;
   }

   bool IsVerbose() override {
     return false;
   }

   int GetMinSdkVersion() override {
     return 0;
   }

  private:
   std::string empty_;
   StdErrDiagnostics diagnostics_;
   NameMangler name_mangler_;
   SymbolTable symbol_table_;
 };

 static void EmitDiffLine(const Source& source, const StringPiece& message) {
   std::cerr << source << ": " << message << "\n";
 }

 static bool IsSymbolVisibilityDifferent(const Visibility& vis_a, const Visibility& vis_b) {
   return vis_a.level != vis_b.level;
 }

 template <typename Id>
 static bool IsIdDiff(const Visibility::Level& level_a, const Maybe<Id>& id_a,
                      const Visibility::Level& level_b, const Maybe<Id>& id_b) {
   if (level_a == Visibility::Level::kPublic || level_b == Visibility::Level::kPublic) {
     return id_a != id_b;
   }
   return false;
 }

 static bool EmitResourceConfigValueDiff(IAaptContext* context, LoadedApk* apk_a,
                                         ResourceTablePackage* pkg_a, ResourceTableType* type_a,
                                         ResourceEntry* entry_a, ResourceConfigValue* config_value_a,
                                         LoadedApk* apk_b, ResourceTablePackage* pkg_b,
                                         ResourceTableType* type_b, ResourceEntry* entry_b,
                                         ResourceConfigValue* config_value_b) {
   Value* value_a = config_value_a->value.get();
   Value* value_b = config_value_b->value.get();
   if (!value_a->Equals(value_b)) {
     std::stringstream str_stream;
     str_stream << "value " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
                << " config=" << config_value_a->config << " does not match:\n";
     value_a->Print(&str_stream);
     str_stream << "\n vs \n";
     value_b->Print(&str_stream);
     EmitDiffLine(apk_b->GetSource(), str_stream.str());
     return true;
   }
   return false;
 }

 static bool EmitResourceEntryDiff(IAaptContext* context, LoadedApk* apk_a,
                                   ResourceTablePackage* pkg_a, ResourceTableType* type_a,
                                   ResourceEntry* entry_a, LoadedApk* apk_b,
                                   ResourceTablePackage* pkg_b, ResourceTableType* type_b,
                                   ResourceEntry* entry_b) {
   bool diff = false;
   for (std::unique_ptr<ResourceConfigValue>& config_value_a : entry_a->values) {
     ResourceConfigValue* config_value_b = entry_b->FindValue(config_value_a->config);
     if (!config_value_b) {
       std::stringstream str_stream;
       str_stream << "missing " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
                  << " config=" << config_value_a->config;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     } else {
       diff |=
           EmitResourceConfigValueDiff(context, apk_a, pkg_a, type_a, entry_a, config_value_a.get(),
                                       apk_b, pkg_b, type_b, entry_b, config_value_b);
     }
   }

   // Check for any newly added config values.
   for (std::unique_ptr<ResourceConfigValue>& config_value_b : entry_b->values) {
     ResourceConfigValue* config_value_a = entry_a->FindValue(config_value_b->config);
     if (!config_value_a) {
       std::stringstream str_stream;
       str_stream << "new config " << pkg_b->name << ":" << type_b->type << "/" << entry_b->name
                  << " config=" << config_value_b->config;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     }
   }
   return false;
 }

 static bool EmitResourceTypeDiff(IAaptContext* context, LoadedApk* apk_a,
                                  ResourceTablePackage* pkg_a, ResourceTableType* type_a,
                                  LoadedApk* apk_b, ResourceTablePackage* pkg_b,
                                  ResourceTableType* type_b) {
   bool diff = false;
   for (std::unique_ptr<ResourceEntry>& entry_a : type_a->entries) {
     ResourceEntry* entry_b = type_b->FindEntry(entry_a->name);
     if (!entry_b) {
       std::stringstream str_stream;
       str_stream << "missing " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     } else {
       if (IsSymbolVisibilityDifferent(entry_a->visibility, entry_b->visibility)) {
         std::stringstream str_stream;
         str_stream << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
                    << " has different visibility (";
         if (entry_b->visibility.level == Visibility::Level::kPublic) {
           str_stream << "PUBLIC";
         } else {
           str_stream << "PRIVATE";
         }
         str_stream << " vs ";
         if (entry_a->visibility.level == Visibility::Level::kPublic) {
           str_stream << "PUBLIC";
         } else {
           str_stream << "PRIVATE";
         }
         str_stream << ")";
         EmitDiffLine(apk_b->GetSource(), str_stream.str());
         diff = true;
       } else if (IsIdDiff(entry_a->visibility.level, entry_a->id, entry_b->visibility.level,
                           entry_b->id)) {
         std::stringstream str_stream;
         str_stream << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
                    << " has different public ID (";
         if (entry_b->id) {
           str_stream << "0x" << std::hex << entry_b->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << " vs ";
         if (entry_a->id) {
           str_stream << "0x " << std::hex << entry_a->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << ")";
         EmitDiffLine(apk_b->GetSource(), str_stream.str());
         diff = true;
       }
       diff |= EmitResourceEntryDiff(context, apk_a, pkg_a, type_a, entry_a.get(), apk_b, pkg_b,
                                     type_b, entry_b);
     }
   }

   // Check for any newly added entries.
   for (std::unique_ptr<ResourceEntry>& entry_b : type_b->entries) {
     ResourceEntry* entry_a = type_a->FindEntry(entry_b->name);
     if (!entry_a) {
       std::stringstream str_stream;
       str_stream << "new entry " << pkg_b->name << ":" << type_b->type << "/" << entry_b->name;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     }
   }
   return diff;
 }

 static bool EmitResourcePackageDiff(IAaptContext* context, LoadedApk* apk_a,
                                     ResourceTablePackage* pkg_a, LoadedApk* apk_b,
                                     ResourceTablePackage* pkg_b) {
   bool diff = false;
   for (std::unique_ptr<ResourceTableType>& type_a : pkg_a->types) {
     ResourceTableType* type_b = pkg_b->FindType(type_a->type);
     if (!type_b) {
       std::stringstream str_stream;
       str_stream << "missing " << pkg_a->name << ":" << type_a->type;
       EmitDiffLine(apk_a->GetSource(), str_stream.str());
       diff = true;
     } else {
       if (type_a->visibility_level != type_b->visibility_level) {
         std::stringstream str_stream;
         str_stream << pkg_a->name << ":" << type_a->type << " has different visibility (";
         if (type_b->visibility_level == Visibility::Level::kPublic) {
           str_stream << "PUBLIC";
         } else {
           str_stream << "PRIVATE";
         }
         str_stream << " vs ";
         if (type_a->visibility_level == Visibility::Level::kPublic) {
           str_stream << "PUBLIC";
         } else {
           str_stream << "PRIVATE";
         }
         str_stream << ")";
         EmitDiffLine(apk_b->GetSource(), str_stream.str());
         diff = true;
       } else if (IsIdDiff(type_a->visibility_level, type_a->id, type_b->visibility_level,
                           type_b->id)) {
         std::stringstream str_stream;
         str_stream << pkg_a->name << ":" << type_a->type << " has different public ID (";
         if (type_b->id) {
           str_stream << "0x" << std::hex << type_b->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << " vs ";
         if (type_a->id) {
           str_stream << "0x " << std::hex << type_a->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << ")";
         EmitDiffLine(apk_b->GetSource(), str_stream.str());
         diff = true;
       }
       diff |= EmitResourceTypeDiff(context, apk_a, pkg_a, type_a.get(), apk_b, pkg_b, type_b);
     }
   }

   // Check for any newly added types.
   for (std::unique_ptr<ResourceTableType>& type_b : pkg_b->types) {
     ResourceTableType* type_a = pkg_a->FindType(type_b->type);
     if (!type_a) {
       std::stringstream str_stream;
       str_stream << "new type " << pkg_b->name << ":" << type_b->type;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     }
   }
   return diff;
 }

 static bool EmitResourceTableDiff(IAaptContext* context, LoadedApk* apk_a, LoadedApk* apk_b) {
   ResourceTable* table_a = apk_a->GetResourceTable();
   ResourceTable* table_b = apk_b->GetResourceTable();

   bool diff = false;
   for (std::unique_ptr<ResourceTablePackage>& pkg_a : table_a->packages) {
     ResourceTablePackage* pkg_b = table_b->FindPackage(pkg_a->name);
     if (!pkg_b) {
       std::stringstream str_stream;
       str_stream << "missing package " << pkg_a->name;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     } else {
       if (pkg_a->id != pkg_b->id) {
         std::stringstream str_stream;
         str_stream << "package '" << pkg_a->name << "' has different id (";
         if (pkg_b->id) {
           str_stream << "0x" << std::hex << pkg_b->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << " vs ";
         if (pkg_a->id) {
           str_stream << "0x" << std::hex << pkg_a->id.value();
         } else {
           str_stream << "none";
         }
         str_stream << ")";
         EmitDiffLine(apk_b->GetSource(), str_stream.str());
         diff = true;
       }
       diff |= EmitResourcePackageDiff(context, apk_a, pkg_a.get(), apk_b, pkg_b);
     }
   }

   // Check for any newly added packages.
   for (std::unique_ptr<ResourceTablePackage>& pkg_b : table_b->packages) {
     ResourceTablePackage* pkg_a = table_a->FindPackage(pkg_b->name);
     if (!pkg_a) {
       std::stringstream str_stream;
       str_stream << "new package " << pkg_b->name;
       EmitDiffLine(apk_b->GetSource(), str_stream.str());
       diff = true;
     }
   }
   return diff;
 }

 class ZeroingReferenceVisitor : public DescendingValueVisitor {
  public:
   using DescendingValueVisitor::Visit;

   void Visit(Reference* ref) override {
     if (ref->name && ref->id) {
       if (ref->id.value().package_id() == kAppPackageId) {
         ref->id = {};
       }
     }
   }
 };

 static void ZeroOutAppReferences(ResourceTable* table) {
   ZeroingReferenceVisitor visitor;
   VisitAllValuesInTable(table, &visitor);
 }

 int Diff(const std::vector<StringPiece>& args) {
   DiffContext context;

   Flags flags;
   if (!flags.Parse("aapt2 diff", args, &std::cerr)) {
     return 1;
   }

   if (flags.GetArgs().size() != 2u) {
     std::cerr << "must have two apks as arguments.\n\n";
     flags.Usage("aapt2 diff", &std::cerr);
     return 1;
   }

   IDiagnostics* diag = context.GetDiagnostics();
   std::unique_ptr<LoadedApk> apk_a = LoadedApk::LoadApkFromPath(flags.GetArgs()[0], diag);
   std::unique_ptr<LoadedApk> apk_b = LoadedApk::LoadApkFromPath(flags.GetArgs()[1], diag);
   if (!apk_a || !apk_b) {
     return 1;
   }

   // Zero out Application IDs in references.
   ZeroOutAppReferences(apk_a->GetResourceTable());
   ZeroOutAppReferences(apk_b->GetResourceTable());

   if (EmitResourceTableDiff(&context, apk_a.get(), apk_b.get())) {
     // We emitted a diff, so return 1 (failure).
     return 1;
   }
   return 0;
 }

 }  // namespace aapt
	/*
	* Copyright (C) 2016 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "android-base/macros.h"

	#include "Flags.h"
	#include "LoadedApk.h"
	#include "ValueVisitor.h"
	#include "process/IResourceTableConsumer.h"
	#include "process/SymbolTable.h"

	using ::android::StringPiece;

	namespace aapt {

	class DiffContext : public IAaptContext {
	public:
	DiffContext() : name_mangler_({}), symbol_table_(&name_mangler_) {
	}

	PackageType GetPackageType() override {
	// Doesn't matter.
	return PackageType::kApp;
	}

	const std::string& GetCompilationPackage() override {
	return empty_;
	}

	uint8_t GetPackageId() override {
	return 0x0;
	}

	IDiagnostics* GetDiagnostics() override {
	return &diagnostics_;
	}

	NameMangler* GetNameMangler() override {
	return &name_mangler_;
	}

	SymbolTable* GetExternalSymbols() override {
	return &symbol_table_;
	}

	bool IsVerbose() override {
	return false;
	}

	int GetMinSdkVersion() override {
	return 0;
	}

	private:
	std::string empty_;
	StdErrDiagnostics diagnostics_;
	NameMangler name_mangler_;
	SymbolTable symbol_table_;
	};

	static void EmitDiffLine(const Source& source, const StringPiece& message) {
	std::cerr << source << ": " << message << "\n";
	}

	static bool IsSymbolVisibilityDifferent(const Visibility& vis_a, const Visibility& vis_b) {
	return vis_a.level != vis_b.level;
	}

	template <typename Id>
	static bool IsIdDiff(const Visibility::Level& level_a, const Maybe<Id>& id_a,
	const Visibility::Level& level_b, const Maybe<Id>& id_b) {
	if (level_a == Visibility::Level::kPublic \|\| level_b == Visibility::Level::kPublic) {
	return id_a != id_b;
	}
	return false;
	}

	static bool EmitResourceConfigValueDiff(IAaptContext* context, LoadedApk* apk_a,
	ResourceTablePackage* pkg_a, ResourceTableType* type_a,
	ResourceEntry* entry_a, ResourceConfigValue* config_value_a,
	LoadedApk* apk_b, ResourceTablePackage* pkg_b,
	ResourceTableType* type_b, ResourceEntry* entry_b,
	ResourceConfigValue* config_value_b) {
	Value* value_a = config_value_a->value.get();
	Value* value_b = config_value_b->value.get();
	if (!value_a->Equals(value_b)) {
	std::stringstream str_stream;
	str_stream << "value " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
	<< " config=" << config_value_a->config << " does not match:\n";
	value_a->Print(&str_stream);
	str_stream << "\n vs \n";
	value_b->Print(&str_stream);
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	return true;
	}
	return false;
	}

	static bool EmitResourceEntryDiff(IAaptContext* context, LoadedApk* apk_a,
	ResourceTablePackage* pkg_a, ResourceTableType* type_a,
	ResourceEntry* entry_a, LoadedApk* apk_b,
	ResourceTablePackage* pkg_b, ResourceTableType* type_b,
	ResourceEntry* entry_b) {
	bool diff = false;
	for (std::unique_ptr<ResourceConfigValue>& config_value_a : entry_a->values) {
	ResourceConfigValue* config_value_b = entry_b->FindValue(config_value_a->config);
	if (!config_value_b) {
	std::stringstream str_stream;
	str_stream << "missing " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
	<< " config=" << config_value_a->config;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	} else {
	diff \|=
	EmitResourceConfigValueDiff(context, apk_a, pkg_a, type_a, entry_a, config_value_a.get(),
	apk_b, pkg_b, type_b, entry_b, config_value_b);
	}
	}

	// Check for any newly added config values.
	for (std::unique_ptr<ResourceConfigValue>& config_value_b : entry_b->values) {
	ResourceConfigValue* config_value_a = entry_a->FindValue(config_value_b->config);
	if (!config_value_a) {
	std::stringstream str_stream;
	str_stream << "new config " << pkg_b->name << ":" << type_b->type << "/" << entry_b->name
	<< " config=" << config_value_b->config;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	}
	return false;
	}

	static bool EmitResourceTypeDiff(IAaptContext* context, LoadedApk* apk_a,
	ResourceTablePackage* pkg_a, ResourceTableType* type_a,
	LoadedApk* apk_b, ResourceTablePackage* pkg_b,
	ResourceTableType* type_b) {
	bool diff = false;
	for (std::unique_ptr<ResourceEntry>& entry_a : type_a->entries) {
	ResourceEntry* entry_b = type_b->FindEntry(entry_a->name);
	if (!entry_b) {
	std::stringstream str_stream;
	str_stream << "missing " << pkg_a->name << ":" << type_a->type << "/" << entry_a->name;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	} else {
	if (IsSymbolVisibilityDifferent(entry_a->visibility, entry_b->visibility)) {
	std::stringstream str_stream;
	str_stream << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
	<< " has different visibility (";
	if (entry_b->visibility.level == Visibility::Level::kPublic) {
	str_stream << "PUBLIC";
	} else {
	str_stream << "PRIVATE";
	}
	str_stream << " vs ";
	if (entry_a->visibility.level == Visibility::Level::kPublic) {
	str_stream << "PUBLIC";
	} else {
	str_stream << "PRIVATE";
	}
	str_stream << ")";
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	} else if (IsIdDiff(entry_a->visibility.level, entry_a->id, entry_b->visibility.level,
	entry_b->id)) {
	std::stringstream str_stream;
	str_stream << pkg_a->name << ":" << type_a->type << "/" << entry_a->name
	<< " has different public ID (";
	if (entry_b->id) {
	str_stream << "0x" << std::hex << entry_b->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << " vs ";
	if (entry_a->id) {
	str_stream << "0x " << std::hex << entry_a->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << ")";
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	diff \|= EmitResourceEntryDiff(context, apk_a, pkg_a, type_a, entry_a.get(), apk_b, pkg_b,
	type_b, entry_b);
	}
	}

	// Check for any newly added entries.
	for (std::unique_ptr<ResourceEntry>& entry_b : type_b->entries) {
	ResourceEntry* entry_a = type_a->FindEntry(entry_b->name);
	if (!entry_a) {
	std::stringstream str_stream;
	str_stream << "new entry " << pkg_b->name << ":" << type_b->type << "/" << entry_b->name;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	}
	return diff;
	}

	static bool EmitResourcePackageDiff(IAaptContext* context, LoadedApk* apk_a,
	ResourceTablePackage* pkg_a, LoadedApk* apk_b,
	ResourceTablePackage* pkg_b) {
	bool diff = false;
	for (std::unique_ptr<ResourceTableType>& type_a : pkg_a->types) {
	ResourceTableType* type_b = pkg_b->FindType(type_a->type);
	if (!type_b) {
	std::stringstream str_stream;
	str_stream << "missing " << pkg_a->name << ":" << type_a->type;
	EmitDiffLine(apk_a->GetSource(), str_stream.str());
	diff = true;
	} else {
	if (type_a->visibility_level != type_b->visibility_level) {
	std::stringstream str_stream;
	str_stream << pkg_a->name << ":" << type_a->type << " has different visibility (";
	if (type_b->visibility_level == Visibility::Level::kPublic) {
	str_stream << "PUBLIC";
	} else {
	str_stream << "PRIVATE";
	}
	str_stream << " vs ";
	if (type_a->visibility_level == Visibility::Level::kPublic) {
	str_stream << "PUBLIC";
	} else {
	str_stream << "PRIVATE";
	}
	str_stream << ")";
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	} else if (IsIdDiff(type_a->visibility_level, type_a->id, type_b->visibility_level,
	type_b->id)) {
	std::stringstream str_stream;
	str_stream << pkg_a->name << ":" << type_a->type << " has different public ID (";
	if (type_b->id) {
	str_stream << "0x" << std::hex << type_b->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << " vs ";
	if (type_a->id) {
	str_stream << "0x " << std::hex << type_a->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << ")";
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	diff \|= EmitResourceTypeDiff(context, apk_a, pkg_a, type_a.get(), apk_b, pkg_b, type_b);
	}
	}

	// Check for any newly added types.
	for (std::unique_ptr<ResourceTableType>& type_b : pkg_b->types) {
	ResourceTableType* type_a = pkg_a->FindType(type_b->type);
	if (!type_a) {
	std::stringstream str_stream;
	str_stream << "new type " << pkg_b->name << ":" << type_b->type;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	}
	return diff;
	}

	static bool EmitResourceTableDiff(IAaptContext* context, LoadedApk* apk_a, LoadedApk* apk_b) {
	ResourceTable* table_a = apk_a->GetResourceTable();
	ResourceTable* table_b = apk_b->GetResourceTable();

	bool diff = false;
	for (std::unique_ptr<ResourceTablePackage>& pkg_a : table_a->packages) {
	ResourceTablePackage* pkg_b = table_b->FindPackage(pkg_a->name);
	if (!pkg_b) {
	std::stringstream str_stream;
	str_stream << "missing package " << pkg_a->name;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	} else {
	if (pkg_a->id != pkg_b->id) {
	std::stringstream str_stream;
	str_stream << "package '" << pkg_a->name << "' has different id (";
	if (pkg_b->id) {
	str_stream << "0x" << std::hex << pkg_b->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << " vs ";
	if (pkg_a->id) {
	str_stream << "0x" << std::hex << pkg_a->id.value();
	} else {
	str_stream << "none";
	}
	str_stream << ")";
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	diff \|= EmitResourcePackageDiff(context, apk_a, pkg_a.get(), apk_b, pkg_b);
	}
	}

	// Check for any newly added packages.
	for (std::unique_ptr<ResourceTablePackage>& pkg_b : table_b->packages) {
	ResourceTablePackage* pkg_a = table_a->FindPackage(pkg_b->name);
	if (!pkg_a) {
	std::stringstream str_stream;
	str_stream << "new package " << pkg_b->name;
	EmitDiffLine(apk_b->GetSource(), str_stream.str());
	diff = true;
	}
	}
	return diff;
	}

	class ZeroingReferenceVisitor : public DescendingValueVisitor {
	public:
	using DescendingValueVisitor::Visit;

	void Visit(Reference* ref) override {
	if (ref->name && ref->id) {
	if (ref->id.value().package_id() == kAppPackageId) {
	ref->id = {};
	}
	}
	}
	};

	static void ZeroOutAppReferences(ResourceTable* table) {
	ZeroingReferenceVisitor visitor;
	VisitAllValuesInTable(table, &visitor);
	}

	int Diff(const std::vector<StringPiece>& args) {
	DiffContext context;

	Flags flags;
	if (!flags.Parse("aapt2 diff", args, &std::cerr)) {
	return 1;
	}

	if (flags.GetArgs().size() != 2u) {
	std::cerr << "must have two apks as arguments.\n\n";
	flags.Usage("aapt2 diff", &std::cerr);
	return 1;
	}

	IDiagnostics* diag = context.GetDiagnostics();
	std::unique_ptr<LoadedApk> apk_a = LoadedApk::LoadApkFromPath(flags.GetArgs()[0], diag);
	std::unique_ptr<LoadedApk> apk_b = LoadedApk::LoadApkFromPath(flags.GetArgs()[1], diag);
	if (!apk_a \|\| !apk_b) {
	return 1;
	}

	// Zero out Application IDs in references.
	ZeroOutAppReferences(apk_a->GetResourceTable());
	ZeroOutAppReferences(apk_b->GetResourceTable());

	if (EmitResourceTableDiff(&context, apk_a.get(), apk_b.get())) {
	// We emitted a diff, so return 1 (failure).
	return 1;
	}
	return 0;
	}

	} // namespace aapt